Fabrication of a W-25%Cu Nanocomposite by High Pressure Torsion

2006 ◽  
Vol 503-504 ◽  
pp. 561-566 ◽  
Author(s):  
I. Sabirov ◽  
Thomas Schöberl ◽  
Reinhard Pippan
Keyword(s):  
Particle Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Coarse Grained ◽  
Tungsten Particle ◽  
Homogeneous Microstructure ◽  
Different Strains ◽  
Particle Refinement ◽  
Evolution Of Microstructure ◽  
20 Nm

A coarse-grained W-25%Cu composite with a tungsten particle size between 2 and 10 μm is subjected to high pressure torsion (HPT) at room temperature to different strains. The evolution of microstructure with increasing strain is studied. At low strains (εeq ≤ 16), an inhomogeneous deformation of the material is found. This inhomogeneity is studied in detail by nanoindentation experiments. At larger strains (εeq ≥ 16), a fragmentation of tungsten particles is observed. The specimen deformed to a strain of 256 exhibits a homogeneous microstructure with a tungsten particle size between 10 and 20 nm. A further increase of strain does not cause a further significant tungsten particle refinement. A possibility of industrial application of HPT to produce nanocomposite materials is discussed.

Mechanical Behavior and Stress-Induced Martensitic Transformation in Nanocrystalline Ti49.4Ni50.6 Alloy

2008 ◽  
Vol 584-586 ◽  
pp. 470-474 ◽  
Author(s):  
Egor Prokofiev ◽  
Dmitriy Gunderov ◽  
Alexandr Lukyanov ◽  
Vladimir Pushin ◽  
Ruslan Valiev
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Martensitic Transformation ◽  
Ultimate Tensile Strength ◽  
High Pressure Torsion ◽  
Coarse Grained ◽  
High Yield ◽  
D 20 ◽  
20 Nm ◽  
High Ultimate Tensile Strength

Amorphous-nanocrystalline Ti49.4Ni50.6 alloy in the shape of a disc 20 mm in diameter has been successfully produced using high pressure torsion (HPT). Application of HPT and annealing at temperatures of 300–550°C resulted in formation of a nanocrystalline (NC) structure with the grain size (D) about 20–300 nm. The HPT samples after annealing at Т = 400°C with the D= 20 nm possess high yield stress and high ultimate tensile strength (more than 2000 MPa). There is an area of strain-induced transformation B2-B19’ on the tensile curve of the samples with the grain size D =20 nm. The stress of martensitic transformation (σm) of samples is 450 MPa, which is three times higher than σm in the initial coarse-grained state (σm ≈ 160 MPa). The HPT samples after annealing at Т = 550°C with the D= 300 nm possess high ductility (δ>60 %) and high ultimate tensile strength (about 1000 MPa).

scholarly journals Evolution of microstructure and hardness in Hf25Nb25Ti25Zr25 high-entropy alloy during high-pressure torsion

2019 ◽  
Vol 788 ◽  
pp. 318-328 ◽  
Author(s):  
Jenő Gubicza ◽  
Anita Heczel ◽  
Megumi Kawasaki ◽  
Jae-Kyung Han ◽  
Yakai Zhao ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Evolution Of Microstructure

Microstructure and Microhardness of Copper Subjected to High Pressure Torsion

2011 ◽  
Vol 194-196 ◽  
pp. 712-715 ◽  
Author(s):  
Zi Ling Xie ◽  
Lin Zhu Sun ◽  
Fang Yang ◽  
Xiao Bing Li
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Type Equation ◽  
Longitudinal Section ◽  
Dislocation Cell ◽  
Subgrain Structure ◽  
Structure Morphology ◽  
Evolution Of Microstructure ◽  
Equiaxed Grains ◽  
Variation Tendency

Experiments were conducted on copper subjected to High Pressure Torsion to investigate the evolution of microstructure and microhardness with shear strain, γ. Observations have been carried out in the longitudinal section for a proper demonstration of the structure morphology. An elongated dislocation cell/subgrain structure was observed at relatively low strain level. With increasing strain, the elongated subgrains transformed into elongated grains and finally into equiaxed grains with high angle grain boundaries. Measurements showed the hardness increases with increasing γ then tends to saturations when γ >5. The variation tendency of microhardness with γ can be simulated by Voce-type equation.

scholarly journals Evolution of microstructure and hardness during artificial aging of an ultrafine-grained Al-Zn-Mg-Zr alloy processed by high pressure torsion

2020 ◽  
Vol 55 (35) ◽  
pp. 16791-16805
Author(s):  
Jenő Gubicza ◽  
Moustafa El-Tahawy ◽  
János L. Lábár ◽  
Elena V. Bobruk ◽  
Maxim Yu Murashkin ◽  
...  
Keyword(s):  
High Pressure ◽  
Dislocation Density ◽  
Grain Boundaries ◽  
Artificial Aging ◽  
High Pressure Torsion ◽  
Secondary Phase ◽  
Aging Effect ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Evolution Of Microstructure

Abstract An ultrafine-grained (UFG) Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by high pressure torsion (HPT) technique and then aged at 120 and 170 °C for 2 h. The changes in the microstructure due to this artificial aging were studied by X-ray diffraction and transmission electron microscopy. It was found that the HPT-processed alloy has a small grain size of about 200 nm and a high dislocation density of about 8 × 1014 m−2. The majority of precipitates after HPT are Guinier–Preston (GP) zones with a size of ~ 2 nm, and only a few large particles were formed at the grain boundaries. Annealing at 120 and 170 °C for 2 h resulted in the formation of stable MgZn2 precipitates from a part of the GP zones. It was found that for the higher temperature the fraction of the MgZn2 phase was larger and the dislocation density in the Al matrix was lower. The changes in the precipitates and the dislocation density due to aging were correlated to the hardness evolution. It was found that the majority of hardness reduction during aging was caused by the annihilation of dislocations and some grain growth at 170 °C. The aging effect on the microstructure and the hardness of the HPT-processed specimen was compared to that observed for the UFG sample processed by equal-channel angular pressing. It was revealed that in the HPT sample less secondary phase particles formed in the grain boundaries, and the higher amount of precipitates in the grain interiors resulted in a higher hardness even after aging.

An Investigation of Microtexture Evolution in an AlMgSi Alloy Processed by High-Pressure Torsion

2011 ◽  
Vol 702-703 ◽  
pp. 165-168 ◽  
Author(s):  
Aicha Loucif ◽  
Thierry Baudin ◽  
François Brisset ◽  
Roberto B. Figueiredo ◽  
Rafik Chemam ◽  
...  
Keyword(s):  
Grain Size ◽  
High Pressure ◽  
Distribution Function ◽  
High Pressure Torsion ◽  
Electron Backscatter Diffraction ◽  
Orientation Distribution ◽  
Homogeneous Microstructure ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Almgsi Alloy

This investigation uses electron backscatter diffraction (EBSD) to study the development of microtexture with increasing deformation in an AlMgSi alloy having an initial grain size of about 150 µm subjected to high pressure torsion (HPT) up to a total of 5 turns. An homogeneous microstructure was achieved throughout the disc sample at high strains with the formation of ultra-fine grains. Observations based on orientation distribution function (ODF) calculation reveals the presence of the torsion texture components often reported in the literature for f.c.c. materials. In particular, the C {001}<110> component was found to be dominant. Furthermore, no significant change in the texture sharpness was observed by increasing the strain.

Evolution of microstructure and hardness in aluminum processed by High Pressure Torsion Extrusion

2019 ◽  
Vol 762 ◽  
pp. 138074 ◽  
Author(s):  
Babak Omranpour ◽  
Yulia Ivanisenko ◽  
Roman Kulagin ◽  
Lembit Kommel ◽  
E. Garcia Sanchez ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressure Torsion ◽  
Evolution Of Microstructure

Phase Transformations in Pearlitic Steels Induced by Severe Plastic Deformation

2006 ◽  
Vol 114 ◽  
pp. 133-144 ◽  
Author(s):  
Julia Ivanisenko ◽  
Ian MacLaren ◽  
Xavier Sauvage ◽  
Ruslan Valiev ◽  
Hans Jorg Fecht
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Pearlitic Steel ◽  
Carbon Steels ◽  
Coarse Grained ◽  
Cold Plastic Deformation ◽  
The Stability ◽  
Nanocrystalline Ferrite

The paper presents an overview of a number of unusual phase transformations which take place in pearlitic steels in conditions of the severe deformation, i.e. combination of high pressure and strong shear strain. Strain-induced cementite dissolution is a well-documented phenomenon, which occurs during cold plastic deformation of pearlitic steels. Recently new results which can shed additional light on the mechanisms of this process were obtained thanks to 3DAP and HRTEM investigations of pearlitic steel deformed by high pressure torsion (HPT). It was shown that the process of cementite decomposition starts by carbon depletion from the carbides, which indicates that the deviation of cementite’s chemical composition from the stoichiometric is the main reason for thermodynamic destabilisation of cementite during plastic deformation. Important results were obtained regarding the distribution of released carbon atoms in ferrite. It was experimentally confirmed that carbon segregates to the dislocations and grain boundaries of nanocrystalline ferrite. Another unusual phase transformation taking place in nanocrystalline pearlitic steel during room temperature HPT is a stress induced α→γ transformation, which never occurs during conventional deformation of coarse grained iron and carbon steels. It was concluded that this occurred due to a reverse martensitic transformation. The atomistic mechanism and the thermodynamics of the transformation, as well as issues related to the stability of the reverted austenite will be discussed.

A comparative study on the evolution of microstructure and hardness during monotonic and cyclic high pressure torsion of CoCuFeMnNi high entropy alloy

2019 ◽  
Vol 34 (5) ◽  
pp. 732-743 ◽  
Author(s):  
Reshma Sonkusare ◽  
Nimish Khandelwal ◽  
Pradipta Ghosh ◽  
Krishanu Biswas ◽  
Nilesh Prakash Gurao
Keyword(s):  
High Pressure ◽  
Comparative Study ◽  
High Pressure Torsion ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Image Position ◽  
Evolution Of Microstructure

Abstract

Evolution of Microstructure and Microhardness in Ti-15Mo β-Ti Alloy Prepared by High Pressure Torsion

2016 ◽  
Vol 879 ◽  
pp. 2555-2560 ◽  
Author(s):  
Kristína Václavová ◽  
Josef Stráský ◽  
Jozef Veselý ◽  
Svetlana Gatina ◽  
Veronika Polyakova ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Dislocation Density ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Positron Annihilation Spectroscopy ◽  
Equivalent Strain ◽  
Ti Alloys ◽  
Evolution Of Microstructure ◽  
Metastable Beta

The main aim of this study is to analyze the effect of the severe plastic deformation (SPD) on the mechanical properties and defect structure of metastable beta Ti alloys. Experiments were performed on two different β-Ti alloys: Ti-15Mo and Ti-6.8Mo-4.5Fe-1.5Al which were subjected to severe plastic deformation (SPD) by high pressure torsion (HPT). The increase of hardness with increasing equivalent strain was determined by microhardness mapping. Dislocation density was studied by advanced techniques of positron annihilation spectroscopy (PAS). Microhardness and dislocation density increases with increasing equivalent strain inserted by severe plastic deformation.

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